Portrait

Description:

Portrait of an encysted individual of the synurophyte flagellate Mallomonas akrokomos (Ruttner in Pascher,1913). Mallomonas is a very large genus with over 120 recognized species. Cells are solitary and biflagellate although the short flagellum is usually not visible by light microscopy (no flagellum is seen in this encysted cell). Chloroplasts are either double or single and bilobed. The chloroplasts of Mallomonas differ from those of chrysophytes in that they contain chlorophyll a and c1 but not chlorophyll c2. A red stigma is absent. Siliceous scales and bristles cover cells. Both are formed intracellularly then extruded to the cell surface where the bristles then articulate with or adhere to the scales. Taxonomy is based on scale and bristle ultrastructure. In M. akrokomos, only a few anterior apical siliceous scales bear long serrated bristles almost the length of the cell. Small flat scales cover the body (not seen in this image). From a freshwater pond near Boise, Idaho. DIC optics.